I'm with you until your step 10. I don't see how you deduced that the right side of clue 7 could only be Istryn or 345K.
At your step 10, I would replace the steps with the following.
We're going to prove that PLC 120 can only be 43, but it is going to take a few steps to do that. One of the steps is going to involve looking at 51 and MKP 427 and noting that none of the planets can be associated with that particular combination.
First use clue 7 to get a few more Xs.
The left side doesn't help because the intersection of 345K and Theros doesn't have any other Xs in the row and column.
The right side is loaded.
The intersection of 45 and ZQ has 2 extra Xs in the row (MKP, PLC) and 2 Xs in the column (43, 49). Use this to deduce that Theros and 345K cannot be MKP or PLC. Other Xs can be placed as well, but for this exercise I am focused on the specific goal of showing that PLC can only be 43.
Now we notice that Theros can only be VJD amd ZQ. More importantly, MKP can now only be Cheelia and Istryn. The other three columns for MKP are X'd out.
51 can only be Quael, Theros, and Zhezios. MKP cannot be any of these three since it can only be Cheelia and Istryn.
So the combination of 51 and MKP doesn't work. That combination could not be associated with any of the planets. We can place an X in the intersection of 51 and MKP 491.
Clue 6 says that MKP has to be 2 years more than 295K. So 295K can no longer be 49.
Clue 1 says that 295K must be greater than PLC, and now 295K can only be 45 and 47. Since PLC can only be 43 and 47 at this point, the only way for PLC to be less than 295K is for PLC 120 to be 43.
Things fall into place after this, and soon Theros will be 51. Clue 4 says that 243K must be Istryn or 51, and since 51 is Theros at this point, 243K has to be Istryn or Theros. This will lead to 243K = ZQ 75 = Theros.
The solution is:
43 - Zhezios - PLC - 540K
45 - Quael - HV - 345K
47 - Cheelia- VJD - 295K
49 - Istryn - MKP - 650K
51 - Theros - ZQ - 243K
Last edited by zenobia43; 03-25-2013 at 12:21 AM.